Anemia is a blood condition in which there is a reduction in number of red blood cells, and the amount of hemoglobin contained in the red blood cells is also reduced. Anemia is generally screened on the basis of measurement results of items such as the red blood cell count (RBC), amount of hemoglobin (HGB), hematocrit value (HCT), mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC) and the like obtained from a blood cell analyzer. However, it is difficult to distinguish the type of anemia by such a screening examination even though the degree of anemia can be determined. Since there are various causes of anemia, a physician can not be sure of the precise treatment to pursue because the type of anemia can not be identified.
Iron deficiency anemia and β thalassemia, for example, are caused by blood disease. Both diseases are caused by impeded production of red blood cells, and exhibit low values for MCV and MCH. It is difficult to distinguish between iron deficiency anemia and β thalassemia because low hemoglobin is a characteristic of small cells. Furthermore, it is difficult to differentiate between mild (minor) cases of β thalassemia and iron deficiency anemia.
The following facts are known based on this background and experiments were performed to classify types of anemia based on information obtained from blood cell analyzers.
(1) U.S. Pat. No. 4,735,504 discloses art which provides information concerning erythrocytic disease and anemic conditions through the determination of individual red cell volume (V) and hemoglobin concentration (HC) by flowing a sample liquid containing blood cells through a flow cell and detecting and analyzing two types of light signals which are emitted from the particles at different angles.
(2) Japanese Laid-Open Patent Publication No. 11-326315 discloses art which discriminates between juvenile blood, iron deficiency anemia, and β thalassemia foremost by utilizing a predetermined method on a plurality of data obtained from a blood analyzer.
(3) U.S. Pat. No. 6,535,836 discloses art which determines blood anomalies by setting a lower limit value and an upper limit value determined from the particle size distribution of normal blood on a particle size distribution curve for red blood cells.
(4) U.S. Pat. No. 6,535,836 discloses art which determines iron metabolism anomalies by combining three parameters obtained from several types of clinical examinations as a method for identifying anemia. The parameters used include the percentage of low hemoglobin red blood cells (HRC %) and the hemoglobin content in reticulocytes (CHr).
(5) US Laid-Open Patent Publication No. 2005-0219527 discloses art which discriminates types of anemia by calculating the reticulocyte hemoglobin content (RET-He) and hemoglobin content in mature red blood cells (RBC-He) from the forward scatter light intensity and the side fluorescent light intensity coming from individual blood cells obtained from a blood analyzer.
Since several examinations are normally necessary to diagnose anemia, it would be extremely beneficial from the perspective of clinical examinations if suitable treatment could be provided at an early stage and at low cost using only a blood cell analyzer without performing a special examination to provide useful identification information.